Computer-assisted coloring and illuminating based on a region-tree structure

Nascimento Renata, Queiroz Fabiane, Rocha Allan, Ren Tsang, Mello Vinicius, Peixoto, Peixoto Adelailson

Description

Colorization and illumination are key processes for creating animated cartoons. Computer assisted methods have been incorporated in animation/illustration systems to reduce the artists' workload. This paper presents a new method for illumination and colorization of 2D drawings based on a region- tree representation. Starting from a hand-drawn cartoon, the proposed method extracts geometric and topological information and builds a tree structure, ensuring independence among parts of the drawing, such as curves and regions. Based on this structure and its attributes, a colorization method that propagates through consecutive frames of animation is proposed, combined with an interpolation method that accurately computes a normal mapping for the illumination process. Different operators for curve and region attributes can be applied independently, obtaining different rendering effects.

Sujets

• Illumination
• Colorization
• Animation

Informations

• Publié par: biomed
• Publié le: 01 janvier 2012
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Nascimentoet al.SpringerPlus2012,1:1 http://www.springerplus.com/content/1/1/1

a SpringerOpen Journal

R E S E A R C HOpen Access Computerassisted coloring and illuminating based on a regiontree structure 1* 23 25 4 Renata Nascimento, Fabiane Queiroz , Allan Rocha , Tsang Ing Ren , Vinicius Melloand Adelailson Peixoto

Abstract Colorization and illumination are key processes for creating animated cartoons. Computer assisted methods have been incorporated in animation/illustration systems to reduce the artists’workload. This paper presents a new method for illumination and colorization of 2D drawings based on a region tree representation. Starting from a handdrawn cartoon, the proposed method extracts geometric and topological information and builds a tree structure, ensuring independence among parts of the drawing, such as curves and regions. Based on this structure and its attributes, a colorization method that propagates through consecutive frames of animation is proposed, combined with an interpolation method that accurately computes a normal mapping for the illumination process. Different operators for curve and region attributes can be applied independently, obtaining different rendering effects. Keywords:2D drawing, Regiontree, Illumination, Colorization, Animation

Introduction Since the 1960s, computers became a great ally in the production of animated films, contributing to several areas that goes from the creation to the final touches [1]. In the conventional production of an animation sequence, first of all is necessary a representation of frame by frame [2]. Even today, this technique is used in the production of 2D animated cartoons in which each frame is represented by a freehand sketch. Although assisted animation accelerate the procedure, it still has many limitations which drives one of the lar gest areas of research in computer graphics: Computer Animation. In the conventional process of computer assisted car toon animation, the entire process for the production is very costly and may even take months for a short ani mation to be finished. Among the biggest challenges of an automated solution, the production of inbetweening and frame colorization as mentioned by [3] is of great importance. Two important, although tedious, steps in the produc tion of animated cartoons are colorization and

* Correspondence: [e-mail]rio.br 1 Department of Mathematics, PUCRio, Rio de Janeiro, Brazil Full list of author information is available at the end of the article

illumination. The colorization process transfers the col ors from a single frame to the subsequent frames. The most common colorization approaches [4,5] use struc tures containing topological information of the drawing, like regions, curves, and graphs, called topological structures. Although these topological structures perform well in the colorization process, they are not commonly exploited in the illumination process of the animation. The illumination process calculates the interaction of the cartoon with light present in a 3D environment, and is an important task in cartoon rendering, since it helps to produce different effects and styles in the animation sequence.

Contributions This paper presents three main contributions. The first one is a new regiontree structure that explores local spacial information in a single frame. The second contri bution is a method based on the regiontree to illumi nate the objects, by approximating lighting on 2D drawings using a direct and spherepreserving interpola tion. Third, we propose a recursive tracking method for color transfer based on the regiontree. This new approach improves more effective associations of

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